1. Field of Invention
The present invention relates generally to the field of communications systems, and more particularly in one exemplary aspect to controlling the distribution of user access clients to devices.
2. Description of Related Technology
Access control is required for secure communication in most prior art wireless radio communication systems. As an example, one simple access control scheme might comprise: (i) verifying the identity of a communicating party, and (ii) granting a level of access commensurate with the verified identity. Within the context of an exemplary cellular system (e.g., Universal Mobile Telecommunications System (UMTS)), access control is governed by an access control client, referred to as a Universal Subscriber Identity Module (USIM) executing on a physical Universal Integrated Circuit Card (UICC). The USIM access control client authenticates the subscriber to the UMTS cellular network. After successful authentication, the subscriber is allowed access to the cellular network. As used hereinafter, the term “access control client” refers generally to a logical entity, either embodied within hardware or software, suited for controlling access of a first device to a network. Common examples of access control clients include the aforementioned USIM, CDMA Subscriber Identification Modules (CSIM), IP Multimedia Services Identity Module (ISIM), Subscriber Identity Modules (SIM), Removable User Identity Modules (RUIM), etc.
Traditionally, the USIM (or more generally “SIM”) performs the well known Authentication and Key Agreement (AKA) procedure, which verifies and decrypts the applicable data and programs to ensure secure initialization. Specifically, the USIM must both (i) successfully answer a remote challenge to prove its identity to the network operator, and (ii) issue a challenge to verify the identity of the network.
Prior art SIM operation allows a subscriber to change between multiple different phones for a carrier network. Specifically, the subscriber information (e.g., billing account, phone number, etc.) is tied to the SIM card, not the phone itself. However, in some business models, mobile phones are heavily subsidized by the carrier; in order to recoup the cost of the subsidy, the subscriber is “locked” to the carrier for a minimum term.
Existing solutions have proven to be ineffective for preventing illicit “breaking” of subsidy-locked devices; i.e., customers may hack the device software and disable the subsidy lock. A high end phone that has been obtained or purchased at subsidized value and broken can be illegally resold at a profit. Consequently, a new black market has arisen for “broken” high end phones which can be used with any carrier.
Accordingly, new solutions are needed for enforcing subsidy locking. Ideally, such solutions should prevent use or activation of a device with an unauthorized user access client. Moreover, the improved methods and apparatus ideally would not rely on unsecured or lightly secured device hardware or software (i.e., elements which can be broken).